Individual amino acids are produced commercially in four ways:
(a) Separation of the amino acids from naturally occurring and renewable raw materials (e.g. chicken feathers, pig bristles); PA0 (b) Chemical synthesis (e.g. DL-methionine); PA0 (c) Enzymatic production from chemical precursors (e.g. L-methionine); PA0 (d) Microbiological production, fermentation (e.g. L-lysine, L-threonine, L-tryptophan).
In all these processes and methods the separation and isolation of the amino acids is one of the essential process steps.
For this purpose organic ion-exchange resins are frequently used.
L-lysine is e.g. adsorbed on strongly acidic ion exchanger resins of the NH4.sup.+ type, at a pH value of 0.5 to 3, the loaded exchanger is then eluted with ammonia water and the desired L-lysine hydrochloride formed by addition of hydrochloric acid (see U.S. Pat. No. 3,565,951).